Summary of Significant Accounting Policies - Summary of Oil and Gas Properties (Detail) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Mineral interests in properties: | ||
| Unproved leasehold costs | $ 28,737 | $ 33,596 |
| Proved leasehold costs | 60,077 | 44,643 |
| Wells and related equipment and facilities | 1,819,836 | 1,774,314 |
| Support equipment | 8,459 | 8,002 |
| Uncompleted wells, equipment and facilities | 13,468 | 9,219 |
| Total costs | 1,930,577 | 1,869,774 |
| Less accumulated depreciation, depletion and amortization | (850,301) | (780,412) |
| Net capitalized costs | $ 1,080,276 | $ 1,089,362 |
| X | ||||||||||
- Definition Amount of accumulated depreciation, depletion, amortization and valuation allowance relating to oil and gas producing activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition The sum of capitalized costs relating to oil and gas producing activities before accounting for accumulated depreciation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- References No definition available.
|
| X | ||||||||||
- Definition Net amount of capitalized costs relating to oil and gas producing activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Capitalized costs of proved properties incurred for any combination mineral interests acquisitions; wells and related equipment; support equipment and facilities; and uncompleted wells and equipment and other costs not previously disclosed within this table. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Capitalized costs incurred for support equipment and facilities used in oil and gas producing activities (such as seismic equipment, drilling equipment, construction and grading equipment, vehicles, repair shops, warehouses, supply points, camps, and division, district, or field offices). Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Capitalized costs of which include those incurred to (1) drill and equip wells that are not yet completed (2) acquire or construct equipment and facilities that are not yet installed. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Capitalized costs of unproved properties incurred for any combination mineral interests acquisitions and other costs not previously disclosed within this table. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
- Definition Capitalized costs which include those incurred to (1) to drill and equip those exploratory wells and exploratory-type stratigraphic test wells that have found proved reserves and (2) obtain access to proved reserves and provide facilities for extracting, treating, gathering, storing the oil and gas, including the drilling and equipping of development wells and development-type stratigraphic wells and service wells. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|